1. Field of the Invention
The present invention relates to a thin film transistor array, and more particularly, to method of manufacturing the thin film transistor array. Even more particularly, the present invention relates to a method of manufacturing a thin film transistor array substrate, the method having a reduced number of steps in a mask process thereof.
2. Description of the Related Art
In general, a liquid crystal display device displays an image by adjusting a transmittance of a liquid crystal material in liquid crystal cells with an electric field. The liquid crystal display device typically includes a liquid crystal display panel in which the liquid crystal cells are disposed, often in a substantially matrix pattern, and a driving circuit which drives the liquid crystal display panel.
The liquid crystal display panel typically includes a thin film transistor array substrate and a color filter array substrate facing disposed opposite to, e.g., facing, the thin film transistor array substrate, and a spacer which maintaining a cell gap between the thin film transistor array substrate and the color filter array substrate. The liquid crystal material is injected into the cell gap.
The thin film transistor array substrate generally includes gate lines, data lines, and switching devices, such as a thin film transistor, for example, disposed at crossing locations of the gate lines and the data lines on the thin film transistor array substrate. In addition, a pixel electrode, substantially defining each of the liquid crystal cells, is connected to each of the thin film transistors. Further, a first alignment film is disposed on the thin film transistor array substrate.
The gate lines and the data lines receive signals from the driving circuits via respective pad parts. Based on a scan signal supplied to a gate line, for example, the thin film transistor supplies the pixel electrode with a pixel voltage signal supplied to the data line from the driving circuits.
The color filter array substrate typically includes color filters disposed corresponding to each of the liquid crystal cells, a black matrix which reflects external light and separates the color filters, a common electrode which supplies a reference voltage to the liquid crystal cells, and a second alignment film.
The liquid crystal display panel is typically fabricated by combining the thin film transistor array substrate with the color filter array substrate which, is manufactured separately from the thin film transistor array substrate, injecting the liquid crystal material therebetween, and sealing thin film transistor array substrate and the color filter array substrate having the liquid crystal material therebetween.
In the liquid crystal display device, a thin film transistor array substrate fabrication involves, for example, a semiconductor formation process which requires a plurality of mask processes, complicating a manufacturing process of the liquid crystal display device. A number of the plurality of mask processes is a major factor contributing to manufacturing costs of the liquid crystal display panel. In attempts to reduce the manufacturing costs, a thin film transistor array substrate has been developed to include a reduced number of steps used in the mask processes. For example, one mask process may include a plurality of sub-processes, such as thin film deposition, cleaning, photolithography, etching, photo-resist stripping and inspection processes, for example. Recent development efforts have resulted in a four-round mask process which eliminates one mask process from an earlier, standard, five-round mask process.
Thus, the thin film transistor array substrate and the manufacturing method thereof of the prior art typically incorporates the four-round mask process. However, the four-round mask process is still a complex manufacturing process which limits reductions of the manufacturing cost. Hence, there is a need for further simplifying the manufacturing process and thereby further reducing the manufacturing cost of the liquid crystal display device.